USB controller and codec running hot ?

[percy]

I got the Audigy 2 NX USB soundcard recently and noticed that even after just a few minutes of operation it would get unusually hot. Not so hot that you can't touch it but too hot for a device that small - both in terms of size and power. So I opened up the box and there some components that get hot the most. But what I am most intrigued about is that the ISP1581 (USB controller?) and the STAC9460S (sigmatel codec) are the hottest chips on board! Why on earth would a codec get so hot ? and the usb chip too ?
What could be going on here ? Any hints ? ideas ? what could I check ?

I think I might rule out a psu(adapter) problem because even on batteries those chips get hot.

Besides that, the whole soundcard draws a pretty hefty 900ma of current - thats almost 5W of power consumption at 5V input. These are the other chips in the box -

Sigmatel STAC9460S - Codec
JRC 4556A - Headphone output
ST MC33078 - Line level output/input dual opamp. Total 4.
Philips UDA1334 - Low Power DAC
Philips ISP1581BD - USB device controller
Creative CA0186 - DSP
Cirrus Logic EP7309 - High-Performance, Low-Power System-on-Chip Enhanced Digital Audio Interface
ST M29W400BB - 4Mbit Flash Memory
ST LD33 - 3.3v regulator (?)
ST LD18 - 1.8v regulator (?)


The DSP, low-power DAC and the Cirrus Logic chip are warm to touch as well, not as hot as the codec and usb controller though, but still I think its too warm for those chips.

Where the heck is all that heat coming from and all that current going ??

[percy]

I take back my statement about the batteries. I did another test with batteries and everything was fine. No heat up.
That was one bad psu!
Now it draws 640ma @ 5.4v.